The present invention relates to an inflatable insulation module that is breathable, i.e. permits the passage of moisture vapor. This inventive module can be incorporated in a wide variety of garments such as suits, vests, jackets, trousers, hats, gloves, socks, and boots. It can also be used in sleeping bags and bedcovers. The inventive module allows the wearer to adjust the amount of insulation being provided depending on the environmental conditions experienced or the activities that the wearer is engaging in. The inventive module is also provided with a relief valve means for reducing pressure in the inflated portion should the module be subjected to sudden or excessive stress. In another embodiment, the inventive module is provided with a seam assembly having increased strength to make it capable of withstanding the rigors of use.
Inflatable garments are well known in the art. The concept of using an air impermeable water vapor permeable material to form the inflatable portion of an insulating module is also known. U.K. Patent Publication 2,317,102 A describes such a module. The air impermeable, water vapor permeable material taught in that publication is an unsupported elastic material such as a polyurethane. The material must be sufficiently elastic to compensate for the stresses arising as a result of inflation, flexing or impact. In order to have sufficient strength, the material has to have a minimum thickness of 50 microns and is preferably 100-150 thick. As a result of using relatively thick membranes, the breathability of the module is acknowledged to be reduced. In some embodiments, both sides of the inflatable cavity are formed from such relatively thick membranes that it further reduces breathability.
U.K. Patent Application GB2,323,015A describes a variable thermal insulation material with an inflatable layer created from an envelope of breathable material formed from a laminate arrangement of hydrophilic films that are bonded to microporous substrates. This document prefers the combination of microporous and hydrophilic material sold under the trademark GORE-TEX by W. L. Gore and Associates, Inc. The composite article is arranged so that the inflatable cavity is created by hermetically sealing the hydrophilic materials to each other with the microporous substrate on the outside of the hydrophilic film.
While the invention described in U.K. Patent Application 2,323,015A provides many of the advantages of the present invention in practice, garments have tended to leak or rupture when subject to external stresses such as impact. Improvements to overcome these deficiencies in the prior art are contemplated.
These and other purposes of the present invention will become evident from review of the following specification.
The present invention improves upon and renders practical the invention described in U.K. Patent Application 2,323,015A, as well as other inflatable breathable modules. A wearer may, as a result of athletic activity or carelessness, fall or bump into inanimate objects that place sudden excess pressure on the module most frequently resulting in the splitting of the seams forming the inflatable cavity thereby rendering the module ineffective for further use. U.K. Patent Publication GB 2,317,102 A sought to guard against this problem by using thick unsupported elastic film which, as is acknowledged in that application reduced the breathability of the module.
Previously known methods of manufacture such as the methods described in U.K. Patent Publication GB 2,317,012 A, are based on high energy welding. Two airtight breathable films are joined, commonly through hermetic sealing or high energy welding with or without an adhesive. In general, these welding methods require continuous contact of the films be made to ensure an airtight bond, and would therefore prevent the inclusion of a load bearing structure (fibrous layer) in the seal. To enhance the integrity of the bond, the films used are relatively thick, suffering the disadvantages mentioned above.
Upon inflation of an inflatable module or upon impact of the inflated cavity with an object or the ground, seals may become stressed. Stress can concentrate at angles or endpoints of seals. Microfailures of inflated cavities frequently occur at these stress concentration points, as the stress transfers from the point of the weld or adhesive line to the thin film which is incapable of bearing the stress resulting in microfailures or tears. Film elasticity alone will not prevent microfailures, and in thin breathable, airtight films, microfailures of the fabric will prevent the module from maintaining an inflated or insulated state.
The current invention provides enhanced breathability while at the same time protecting against seam rupture.
In one embodiment, the present invention is an inflatable module having one or more inflatable cavities in the module, wherein the module which is breathable, i.e. permits the passage of moisture vapor, and which further incorporates a pressure relief means for reducing pressure in the inflated portion(s) should the module be subjected to sudden or excessive stress. In a preferred embodiment of the invention, a pressure relief valve is incorporated as the pressure relief mechanism in the inflatable module.
The present invention is also directed to an inflatable breathable module having one or more inflatable cavities in the module, wherein the cavities are formed by sealing one layer of breathable fabric to an adjoining layer of breathable fabric, and which further incorporates a means for increasing the strength of the seals to prevent rupture should the module be subjected to sudden or excessive stress. In preferred embodiment, the seals allow for a continuous bond between the airtight layers and form a structural bond between the inner reinforcing textile layers constituting the interior of the airtight breathable fabrics and the inflatable cavity.